北海湾赤潮形成原因及机理

Reason and mechanism caused red tide in Beihai Bay

通过对北海湾开发盛期（1995～2004年）10a间DIN、DIP、Chla．的分布特征及其与环境条件、环境因子之间关系的分析，探讨了该湾赤潮形成的原因和机理。结果表明：该湾赤潮的形成是以高N高P高Chl．a为主要特征，但P是1995年首次发生赤潮最重要的环境因子，是引发赤潮的内因，而N在该年度赤潮形成的过程中却以外因的作用出现，通过内因而引发赤潮；但在该湾生态环境演变的过程中，2004年的N已在海湾自身增补作用影响下从1995年的外因向内因位置迈进，与P同时跃居内因地位，赤潮的隐患已呈加重趋势。相关分析显示，作为诱发该湾赤潮的N、P营养盐，其来源途径并不一致。DIN突出了陆源径流输入的重大影响作用；而DIP则以海湾自身的再生补充为主，其中湾内沉积物中P的聚积及释放作用是引发该湾赤潮的最重要的内因。

Based on the analysis of relationship between the environmental condition and distribution characteristics of DIN, DIP, Chl. a 1995 - 2004, the discussion on the reasons and mechanism of red tide formed was done. The results show that high N, P and Chl. a are the main characteristics. In 1995, in the first red tide P was the most important environmental factor, intrinsic factor while N was exogenous which acted through P. In the variation of ecological environment in Beihai bay, N effected by the supplement action in the bay in 2004, it is forward the same position with P of intrinsic factor instead of being exogenous in 1995. The hidden trouble of red tide was getting serious. The correlation analysis shows that the source and approach of N and P are different. The important effect of input and runoff from the continents is DIN, while DIP is mainly from the regeneration in the bay itself. The aggregation and discharge of P in the deposit is the most important internal factor.